Initialize

Adds Euler solutions to #6, #8, #11, #5, #48, #49, #41, #423, #4, #14,
  #9, #19, #92, #1, #7, #17, #16, #10, #13, #34, #30, #3, #12, #25, #24,
  #21, #22, #20 and #2.
Rename files so they match NNN pattern (e.g. 004)
Rewrite problems in Julia and Haskell

I've decided to try Julia and Project Euler seemed to be an appropriate
use case for its capabilities. So I did.

When I got stuck, I've used Haskell instead.
I also solved three ones: #3, #6, #50.